Upgrade ESXi in 4 steps

Preparation:

Install VMware vcenter server

Install VMware vsphere tools CLI

Install VMware vclient gui interface

Shutdown all guest instances and then prepare the server for Maintenance Mode

Remember that you need the IP of each ESX server a.k.a [Needed Host Server IP]

Step 1.) Place each host into Maintenance mode

Step 2.)  Start with the first line and apply to each [Needed Host Server]

·        Vicfg-cfgbackup --server [Needed Host Server IP] --save C:\ESXiConfigBackups\[HostNameVersion.txt]

·        vihostupdate.pl -i -bundle C:\Documents and Settings\[user]\My Documents\Downloads\upgrade-from-esxi4.0-to-4.1-update03-800380.zip -url https://[Server  Host Needed_IP]/sdk/webservice

·        vicfg-hostops.pl --server [Server Host Needed IP] --o reboot

·        vihostupdate.pl --server [Server Host Needed IP] - -query

Step 3.) Take [Needed Host Server] out of Maintenance mode

Step 4.) Power up all VMs (Guests) on [Needed Host Server]